JP2000194321A - Driving device for organic EL element - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a driving device for an organic EL element configured in a matrix, power consumption is achieved by maintaining a matrix display even if an organic EL element fails, and by preventing unnecessary current from flowing. To be kept low. SOLUTION: An organic EL element EL1 having a matrix structure is provided.
A constant current circuit Is is connected to the anode-side power supply 1 for driving the EL1-EL33.
1 to Is3 are connected for each line to suppress the current when the organic EL element is short-circuited. Further, a cathode-side power supply 2 for preventing an erroneous occurrence due to a leak current is provided, and constant current circuits Ib1 to Ib3 are connected to the cathode-side power supply 2 to similarly limit the current flowing when the element is short-circuited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a simple matrix type organic EL panel.

[0002]

2. Description of the Related Art FIG. 9 is a circuit diagram showing a schematic configuration of a general organic EL element driving device of this kind. In the figure, reference numeral 1 denotes each organic EL element EL1 arranged in a matrix.
An anode-side power supply that supplies a drive voltage Vs to the EL circuits 1 to 33, and is connected to the anode sides of the organic EL elements EL11 to EL33 via one contact of the switch circuits Ss1 to Ss3 for each line (column). The other contact of Ss3 is connected to a GND (ground) terminal. Reference numeral 2 denotes a cathode-side power supply for supplying a reverse voltage Vb to prevent erroneous lighting due to leakage current flowing through the organic EL elements 11 to EL33. Are connected via one contact of the switch circuits Sb1 to Sb3 to the switch circuits Sb1 to Sb3.
Is connected to a driving GND terminal.

Since the organic EL elements EL11 to EL33 are not perfect rectifiers, a leakage current flows in the opposite direction. Therefore, the organic EL elements EL11 to EL
When an EL panel having a simple matrix configuration of L33 is driven in a dot matrix, there is a case where elements other than the selected pixel emit light due to the leakage current. To prevent this erroneous light emission, see, for example, JP-A-6-30
As disclosed in Japanese Patent No. 1355 and the like, a non-selected anode line is connected to a GND terminal, and a voltage Vb applied to a non-selected cathode line is applied. This voltage Vb
Is a voltage at which the difference from the drive voltage Vs of the anode becomes smaller than the light emission voltage.

Further, as a drive circuit for preventing the above-mentioned erroneous light emission, circuits as shown in FIGS. 10 and 11 have been proposed. In FIG. 10, a pull-up resistor Rb is connected between the cathode side of the organic EL element and the power supply 2, and is directly connected to the GND terminal by a switch circuit Sb. The one shown in FIG. 11 is one in which a constant current circuit Is is interposed between the switch circuit Ss on the anode side of the organic EL element EL and the drive power supply 1, and the power supply of the anode is a constant current.

[0005]

However, in the conventional driving device as described above, in the circuit shown in FIG. 9, for example, when the organic EL element is short-circuited due to a failure, the power supply and the GND terminal are short-circuited. There has been a problem that display is not performed due to a voltage drop and a circuit and a dot matrix are destroyed by an overcurrent. For example, in the state of FIG.
When the element EL11 is short-circuited, the power supply 2 and the GND terminal are short-circuited.

Further, in the circuit shown in FIG. 10 in which a resistor is inserted on the cathode side, the current is limited by the resistance, so that no overcurrent flows, but the cathode side is connected to the GND terminal in order to make the element emit light. Then, a current (Vb / Rb) flows from the cathode side power supply through the resistor, and there is a problem that power consumption increases. FIG.
In the circuit provided with a constant current circuit on the anode side shown in (1), a drive current exceeding the value set as the constant current does not flow, but there is a problem that a short-circuit current may flow from the cathode side.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to prevent a circuit or a dot matrix from being destroyed even if a failure occurs in an organic EL element, and to continue displaying. It is an object of the present invention to provide a driving device for an organic EL element which can reduce power consumption at the same time.

[0008]

The driving device of the organic EL device according to the present invention is constituted as follows.

(1) A driving device for an organic EL element having a matrix structure, wherein a current limiting means is provided at an anode-side power supply or a cathode-side ground terminal for driving the organic EL element, and an erroneous light emission due to a leak current is prevented. Current limiting means is provided at the cathode-side power supply or the anode-side ground terminal, and these are selected.

(2) A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source, and a cathode-side power supply for preventing erroneous light emission due to a leakage current. The current source.

(3) A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source and an anode-side ground for preventing erroneous light emission due to a leak current. Current limiting means was connected to the terminal.

(4) A driving device for an organic EL element having a matrix structure, wherein a positive power supply for driving the organic EL element is used as a constant current source, and a negative power supply for preventing erroneous light emission due to a leak current is provided. A resistor was connected to the circuit for selecting the cathode side power supply.

(5) A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source and an anode-side ground for preventing erroneous light emission due to a leak current. A resistor was connected between the terminal and a circuit for selecting this anode side ground terminal.

(6) In the configuration of (1) or (3), the current limiting means is a constant current circuit.

[0015]

FIG. 1 is a circuit diagram showing the configuration of a first embodiment of the present invention. The same reference numerals as in FIG. 9 denote the same components. This circuit includes the organic EL elements EL11 to EL3
The constant current circuits Is1 to Is3 and Ib1 as current limiting means for each of the anode-side power supply 1 and the cathode-side power supply 2 for each line.
To Ib3, the switch circuits Ss1 to Ss
3, Sb1 to Sb3 are selection means for them.
Other configurations are the same as those in FIG. Note that the constant current circuits Is1 to Is3, Ib1 to Ib3
May be provided at the cathode side GND terminal and the anode side GND terminal, respectively.

In this embodiment, the anode-side power supply 1 or the cathode-side G
The ND terminal is provided with a current limiting mechanism, and the cathode side power supply 2 or the anode side GND terminal is provided with a current limiting mechanism,
When these current limiting mechanisms are unnecessary (power / GND switching), current is not supplied / inflowed. Constant current circuits Is1-Is3, I3 serve as current limiting mechanisms.
Each of the power supplies 1 and 2 is a constant current source using b1 to Ib3.

As described above, by connecting the constant current circuits Is1 to Is3 to the anode-side power supply 1 for driving the organic EL element,
The emission luminance of the organic EL elements EL11 to EL33 can be stabilized, and the current at the time of short circuit between the power supply 1 and the GND terminal can be limited. Also, the constant current circuits Ib1 to Ib3 are connected to the cathode side power supply 2 for preventing erroneous light emission.
Is connected, the current at the time of short circuit between the power supply 2 and the GND terminal can be limited.

FIGS. 2 (a) and 2 (b) are diagrams showing one example of a specific cathode side and anode side circuit of the present embodiment. In the figure, Q1 to Q3 are transistors, Rb and Rs are resistors, 3
Is an analog switch.

FIG. 3 is a circuit diagram showing the configuration of the second embodiment of the present invention. In the present embodiment, the anode side power supply 1 for driving the organic EL element EL is used as a constant current source by the constant current circuit Is, and the constant current circuit Ib is connected to the anode GND terminal for preventing erroneous light emission due to leakage current. Connected. In this configuration, the emission luminance is stabilized, the current at the time of short circuit between the power supply 1 and the GND terminal is limited, and the discharge current of the electric charge charged to the element EL and the power supply 2
The current at the time of short circuit between the terminal and the GND terminal is limited. FIGS. 4A and 4B are diagrams showing one example of a specific cathode side and anode side circuit of the present embodiment. In the figure, Q4 to Q9 indicate transistors, and Rs1 and Rs2 indicate resistors.

FIG. 5 is a circuit diagram showing the configuration of the third embodiment of the present invention. In this circuit, the anode-side power supply 1 is used as a constant current source as in the above-described embodiments, and a resistor Rb is inserted between the cathode-side power supply 2 for preventing erroneous light emission and the switch circuit Sb to connect the power supply 2 to GND. The current at the time of short circuit between terminals is limited. Also in this configuration, no useless current flows when the cathode side is connected to the GND terminal.

FIG. 6 is a diagram showing an example of a specific circuit of this embodiment, and shows an actual example of a circuit on the cathode side. In the figure, Q10 and Q11 are transistors.

FIG. 7 is a circuit diagram showing a configuration of a fourth embodiment of the present invention. In this circuit, the anode-side power supply 1 is used as a constant current source as in the above-described embodiments, and a resistor Rs is inserted between the anode-side GND terminal for preventing erroneous light emission and the switch circuit Ss. With this configuration, the discharge current of the charge charged in the element EL and the current at the time of short-circuit between the power supply 2 and the GND terminal are limited by the resistor Rs. When the anode is driven at a constant current, no current flows through the resistor Rs.

FIG. 8 is a diagram showing an example of a specific circuit of this embodiment, and shows an actual example of a circuit on the anode side. In the figure, Q12 to Q14 are transistors.

Although the embodiments of the present invention have been described above, in the present invention, by limiting the current, even if a failure occurs in the organic EL element and the organic EL element is short-circuited, the circuit, other elements, and the dot matrix can be formed. Destruction can be prevented, and display can be continued even if a partial defect occurs in the display (pixel). At the same time, power consumption can be reduced by preventing useless current. it can.

It is to be noted that the object of the present invention is to make it possible to continue lighting without being affected by a power supply or other parts even if a part of the organic EL element is damaged as described above. Elements EL11, EL21, and EL of the first circuit
In line 31, if the element EL11 is short-circuited, the cathode side of the element EL21, which should not be turned on, is connected to the GND terminal through the element EL, and the element EL21 is turned on. This is unavoidable because it is a matrix circuit. However, although the EL element can be completely short-circuited, the ITO film, which is a conductive line, has a considerably large resistance, so that the above-mentioned turn-on does not become so large.

The organic EL element has a capacity when viewed from the circuit, and must be charged when lit and discharged when not lit. Therefore, it cannot be protected simply by inserting a diode like other elements. In the state of FIG. 1, the elements EL11 and EL31 are charged from the cathode side to the GND terminal side, and are discharged in the opposite direction at the time of lighting.

[0027]

As described above, according to the present invention, the organic E
Even if a failure occurs in the L element, the circuit, other elements, and the dot matrix can be prevented from being damaged, and display can be continued even if pixels are partially lost, and at the same time, useless. There is an effect that the current can be prevented from flowing and the power consumption can be suppressed low.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a circuit according to the first embodiment;

FIG. 3 is a circuit diagram showing a configuration of a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a circuit according to a second embodiment;

FIG. 5 is a circuit diagram showing a configuration of a third embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a circuit according to a third embodiment;

FIG. 7 is a circuit diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a circuit according to a fourth embodiment.

FIG. 9 is a circuit diagram showing a configuration of a conventional example.

FIG. 10 is a circuit diagram showing a configuration of another conventional example.

FIG. 11 is a circuit diagram showing a configuration of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode power supply 2 Cathode power supply 3 Analog switch EL11-EL33 Organic EL element Is1-Is3 Constant current circuit Ib1-Ib3 Constant current circuit Ss1-Ss3 Switch circuit Sb1-Sb3 Switch circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB08 BA06 DA01 DB03 EB00 GA03 5C080 AA06 BB05 CC01 DD18 DD19 EE25 FF01 FF03 FF09 JJ02 JJ03

Claims (6)

[Claims] 1. A driving device for an organic EL element in a matrix configuration, wherein a current limiting means is provided at an anode-side power supply or a cathode-side ground terminal for driving the organic EL element.
A driving device for an organic EL element, wherein a current limiting means is provided in a cathode side power supply or an anode side ground terminal for preventing erroneous light emission due to a leak current, and these are selected. 2. A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source, and a cathode-side power supply for preventing erroneous light emission due to leakage current is used as a constant current. A driving device for an organic EL device, wherein the driving device is a source. 3. A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source, and an anode-side ground terminal for preventing erroneous light emission due to leak current. A driving device for an organic EL device, wherein a current limiting means is connected to the driving device. 4. A driving device for an organic EL element having a matrix structure, wherein a cathode-side power supply for preventing erroneous light emission due to a leak current and an anode-side power supply for driving the organic EL element are used as a constant current source. A driving device for an organic EL element, wherein a resistor is connected to a circuit for selecting a side power supply. 5. A driving device for an organic EL element in a matrix configuration, wherein an anode-side power supply for driving the organic EL element is used as a constant current source, and an anode-side ground terminal for preventing erroneous light emission due to a leak current. A driving device for an organic EL device, wherein a resistor is connected between the circuit and a circuit for selecting the anode-side ground terminal. 6. The driving device for an organic EL device according to claim 1, wherein the current limiting means is a constant current circuit.